(1) Field of the Invention
This invention relates to wells, more specifically to the retrieving of cable from the wells.
(2) Description of the Prior Art
There has long been a problem in the maintenance of oil and gas wells with the recovering of cable and tools lost down the well. Steel cable or wire line is commonly used at drilling sites to lower tools, etc. into the well. Clearly, great lengths of cable must be used. From time to time this cable breaks while it is being raised. When the cable breaks it sinks toward the bottom of the well. Those who are operating the well are faced with either fishing the cable out of the well or drilling a new well altogether. The drilling of a new well is clearly a very expensive alternative. However, in many oilfield operations "time is money" and time spent trying to retrieve the cable could well end up being more expensive. Considerable time may be wasted in trying to withdraw the cable as the cable is very likely to break again as it is drawn up. Also, it may be practically impossible to retrieve the cable by methods in use before this invention.
The actual fishing procedure includes inserting the tool into the well and lowering it by successive lengths of tubing until it comes into contact with the cable. Once the cable has been located or engaged, it must be grasped or grappled or attached by the tool and withdrawn from the well. Problems arise both in the initial attachment step and in keeping the cable securely held as it is pulled out of the well.
Before filing this application, applicant caused a search of the prior art to be made in the United States Patent and Trademark Office. That search produced the following U.S. Pat. Nos.:
Barnes--3,895,837; PA1 Blume--3,330,533; PA1 Sonnier--3,029,098; PA1 Monroe--1,790,387; PA1 Hanlon--1,490,386; PA1 Lower--985,817.
LOWER discloses a corkscrew like fishing tool which is primarily useful for retrieving valves from oil wells. While spiralling members are disclosed, the engaging members are pronged, not threaded.
BARNES and MONROE both disclose fishing spears with the engaging teeth axially aligned on the mandrel.
BLUME discloses a tool with axially oriented engaging hooks which are used in duct cleaning.
The other references discovered by the searcher are of general interest only, and believed to be not as pertinent as those discussed above.